Pressure compensated flow rate controller with BTU meter

ABSTRACT

A constant-flow control valve and BTU meter assembly that has a pressure independent, constant-flow control valve assembly connectable to the fluid-based heating or cooling system. A valve stem is connected to a valve member and is rotatable as a unit relative to a valve body to change the position of valve member to change a fluid flow rate through the valve. The valve member&#39;s position relative to the fluid path is directly related to the fluid flow rate. A BTU meter assembly is connected to the valve stem, which is rotatable relative to the BTU meter assembly. A position sensor of the BTU meter assembly detects a rotational position of the valve stem relative to the BTU body. A controller of the BTU meter assembly determines the fluid flow rate based upon the pressure drop across the valve assembly and the rotational position of the valve stem.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a non-provisional patent application that herebyclaims priority to U.S. Provisional Patent Application No. 61/433,632,titled “Pressure Compensated Flow-Rate Controller With BTU Meter,” filedJan. 18, 2011, and which is incorporated herein in its entirety byreference thereto.

TECHNICAL FIELD

Embodiments of the present invention are directed to flow ratecontrollers and BTU meters.

BACKGROUND

Flow control valves are used extensively to control fluid flow inheating and cooling systems used to control thermal loads in, as anexample, buildings or other spaces. Conventional heating and chilledwater systems system utilized the flow control valves control the flowof fluid through the system as needed to meet the heating or coolingneeds, such as may be indicated by a thermostat or other control system.The systems also typically monitor the amount of energy being used inthe heating and chilled water system via BTU (British Thermal Units)meters.

BTU meters are used in buildings to measure heat consumed in buildingHVAC systems for both performance monitoring and billing purposes. BTUmeters for building applications are most commonly comprised of acomputer connected to a liquid flow meter and temperature sensors beforeand after a heating or cooling load. The flow rate measured multipliedby the temperature difference across the heating or cooling coilmultiplied by a constant is equal to the BTUs transferred to (cooling)or from (heating) the load.

U.S. Pat. No. 5,904,292 discloses an electrically driven valve connectedto a cooling or heating load, such as a coil, with temperature sensorsbefore and after the coil with the system controlled and monitored by acomputer. This valve is not a pressure balanced device so a change inpressure drop across the valve section would result in change in flowrate measured in the built in flow meter. The motor would then need toadjust the stem. While making this adjustment valves in parallel withthe valve undergoing adjustment would then be effected with respect topressure drop. The result of the interdependence on all valves is thatthe flow rates will cycle in rate never reaching a constant flow throughthe heating or cooling coil.

SUMMARY

Aspects of the present invention are directed to flow rate controllerand BTU meter assemblies, systems and methods that overcome drawbacksexperienced in the prior art and provide additional benefits. Inaccordance with aspects of an embodiment include an energy consumptionmonitoring system for a fluid-based heating or cooling system with afluid flow therethrough. The system comprises a heating or coolingdevice, a supply line connected to the heating or cooling device, and areturn line connected to the heating or cooling device. The supply linecarries fluid to the heating or cooling device at a first temperature,and the return line carries fluid from the heating or cooling device ata second temperature different than the first temperature. A firsttemperature sensor is coupled to the supply line and is positioned tomeasure the first temperature, and a second temperature sensor iscoupled to the return line and is positioned to measure the secondtemperature, wherein the temperature difference between the first andsecond temperatures is a temperature change across the heating orcooling device.

The system includes a pressure independent, constant-flow control valveassembly that has a valve body with an inlet and an outlet, a valvechamber therein, and a fluid path extending between the inlet, outletand the valve chamber. An adjustable valve member is in the valvechamber and disposed in the fluid path. A valve stem is connected to thevalve member. The valve stem is rotatable relative to the valve body toadjust the valve member and to adjust a fluid flow rate through thefluid path. The position of the valve member relative to the fluid pathis directly related to the fluid flow rate through the fluid path. Afirst fluid pressure sensor is positioned to measure the fluid pressureof fluid entering the inlet of the valve body, and a second fluidpressure sensor is positioned to measure the fluid pressure of fluidexiting the outlet of the valve body. The difference between the firstand second pressures is the pressure drop across the valve.

A BTU meter assembly is connected to a free end portion of the valvestem projecting from the valve body, wherein the valve stem is rotatablerelative to at least a portion of the BTU meter assembly. The BTU meterassembly comprises a BTU body and a position sensor, which is coupled tothe BTU body and to the valve stem. The position sensor is configured todetect the rotational position of the valve stem relative to the BTUbody. The BTU meter assembly has a controller coupled to the positionsensor, to the first and second pressure sensors, and to the first andsecond temperature sensors. The controller is configured to determinethe fluid flow rate based upon the pressure drop across the valve andthe rotational position of the valve stem. The controller is configuredto determine energy usage of the heating or cooling device in real timebased upon the flow rate and the temperature change across theheating/cooling device.

Aspects of one or more embodiments may include the following: the BTUmeter can include a BTU body and a rotatable fitting connected to theBTU body, wherein the rotatable fitting is fixedly attached to the freeend portion of the valve stem and is rotatable with the valve stem as aunit relative to the BTU and valve bodies. The position sensor iscalibrated to detect the rotational position of the valve stem relativeto a predetermined reference point directly related to a referenceposition of the adjustable valve member in the valve chamber. The BTUmeter assembly is carried by the pressure independent, constant-flowcontrol valve assembly. The heating or cooling device is a component ofa heating and chilled water system. The heating or cooling device can bea heat exchanger, a boiler, a condenser, or a chiller. The valve stem isautomatically adjustable in response to instructions from thecontroller. The valve stem, the valve member, and the rotatable fittingcan be interconnected and rotatable together as a unit relative to theBTU body. The controller can be exterior of the BTU body.

Another aspect of the embodiments provides a constant-flow control valveand BTU meter assembly that comprises a pressure independent,constant-flow control valve assembly connectable to the fluid-basedheating or cooling system. The assembly has a valve body with an inletand an outlet, a valve chamber with a fluid path therein extendingbetween the inlet and outlet, and an adjustable valve member in thevalve chamber and disposed in at least a portion of the fluid path todefine a throttle in the fluid path. A valve stem is connected to thevalve member and is rotatable as a unit relative to the valve body tochange the position of valve member to change a fluid flow rate throughthe valve body. The position of the valve member relative to the fluidpath is directly related to the fluid flow rate through the fluid path.A first fluid pressure sensor is positioned to measure the fluidpressure of fluid entering the inlet of the valve body, and a secondfluid pressure sensor is positioned to measure the fluid pressure offluid exiting the outlet of the valve body. The difference between thefirst and second pressures is the pressure drop across the valveassembly.

A BTU meter assembly is connected to the free end portion of the valvestem, wherein the valve stem is rotatable relative to at least a portionof the BTU meter assembly. The BTU meter assembly has a BTU body and aposition sensor coupled to the BTU body and to the valve stem. Theposition sensor is configured to detect a rotational position of thevalve stem relative to the BTU body. The BTU meter assembly has acontroller coupleable to the position sensor, to the first and secondpressure sensors, and to the first and second temperature sensors. Thecontroller being is to determine the fluid flow rate based upon thepressure drop across the valve assembly and the rotational position ofthe valve stem. The controller is configured to determine energy usageof the heating or cooling device based upon the flow rate and thetemperature change across the heating or cooling device.

Another aspect of the embodiments includes a method of determiningenergy consumption of a fluid-based heating or cooling system with aheating or cooling device and fluid flowing therethrough. The methodcomprises determining a first temperature of fluid flowing in a supplyline to the heating or cooling device, and determining a secondtemperature of fluid flowing in a return line from the heating orcooling device. Further, determining a first fluid pressure of fluidentering an inlet of a pressure independent, constant-flow control valveassembly that controls a flow rate of the fluid in the fluid-basedheating or cooling system. Further, determining a position of the valvestem relative to the valve body or the BTU body, and determining asecond fluid pressure of fluid exiting the outlet of the control valveassembly, wherein a difference between the first and second fluidpressures corresponds to a pressure drop across the valve. Further,determining the flow rate of fluid passing through the control valveassembly based on the pressure drop across the valve and the position ofthe valve stem relative to the valve body or the BTU body, anddetermining energy consumption of the heating or cooling device in realtime based upon the determined flow rate and the temperature changeacross the heating or cooling device.

Aspects of the method can include determining the first temperatureincludes sensing the first temperature with a first temperature sensorcoupled to the controller and coupled to the supply line, anddetermining the second temperature includes sensing the secondtemperature with a second temperature sensor coupled to the controllerand coupled to the return line. The method can include determining theflow rate includes detecting a rotational position of the valve stemrelative to a predetermined reference point associated with at least oneof the valve body or the BTU body. The method can include determiningenergy consumption of the heating or cooling device includes determiningthe energy consumption of at least one of a heat exchanger, a boiler, acondenser, or a chiller. The method can also include determining theposition of the valve stem comprises determining with a position sensora rotational position of the valve stem relative to the valve body orBTU body.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic cross-sectional view of a pressure independentvalve connected to a BTU meter in accordance with an aspect of thedisclosure.

FIG. 1B is an enlarged cross-sectional view of a portion of the pressureindependent valve of FIG. 1A.

FIG. 2 is an isometric view of a flow control valve assembly with anintegral BTU meter in accordance with an embodiment of the presentinvention.

FIG. 3 is another isometric view of the flow control valve assembly withan integral BTU meter of FIG. 1.

FIG. 4 is another isometric view of the flow control valve assembly withan integral BTU meter of FIG. 1.

FIG. 5 is a bottom isometric view of the flow control valve assemblywith an integral BTU meter of FIG. 1.

DETAILED DESCRIPTION

The present invention provides a flow control valve assembly with a flowcontrol valve an integral BTU meter that overcomes drawbacks experiencedin the prior art. The present disclosure describes a flow control valveassembly in accordance with certain embodiments of the presentinvention. Several specific details of the invention are set forth inthe following description and the Figures to provide a thoroughunderstanding of certain embodiments of the invention. One skilled inthe art, however, will understand that the present invention may haveadditional embodiments, and that other embodiments of the invention maybe practiced without several of the specific features described below.

FIG. 1 is a schematic, cross-sectional view of a flow control assembly10 with a pressure compensated flow rate controller 12 and an integralBTU meter 14 in accordance with embodiments of the present invention. Inthe illustrated embodiment, the pressure compensated flow ratecontroller 12 is operatively connected to a computer 13 configured tomonitor temperature sensors 15 before and after a heating or coolingload in a heating and chilled water system 11. The computer 13 can alsomonitor pressure sensors P1, P2 and P3 in addition to valve stemposition (discussed in greater detail below) and an optional airtemperature sensor. The position of an internal rate control piston 26can also be monitored by a proximity sensor 17 that, in turn, ismonitored by the computer 13.

The pressure compensated flow rate controller 12 in at least oneembodiment includes a pressure independent flow control valve 19 thatprovides constant flow rate at the same stem set point with largefluctuations in pressure drop across the valve. Provided a minimumpressure drop is applied to the valve 19, the flow rate through thevalve is very predictable for each stem set point. This rate controltechnology and a pressure independent flow rate controller are describedin detail in U.S. Pat. No. 7,128,086, titled Flow Control Valves, issuedOct. 31, 2006, and which is incorporated herein in its entirety byreference thereto. This constant flow produces a system where valves andmotor driven stems do not cyclically hunt in attempt to produce constantflow.

The computer 13 monitors the stem position and in combination with theP1 and P3 pressure sensors 21 to check for minimum pressure drop toinfer the flow rate. This flow rate is then multiplied by the differencein temperature across the heating or cooling load (e.g. a coil) todetermine the BTU rate being transferred. An alternate to measuring theP1 and P3 sensors 21 is to monitor the position sensor 17 and/or thatthe rate control piston 26 has moved into its throttling position whichwould be caused by a minimum pressure drop applied across the valve.

The stem inference and constant flow without cyclic hunting allows thestem position to substitute the flow meter listed in the 292 patent.Eliminating this flow meter eliminates a multitude of maintenance andcalibration issues (such as fowling turbines in flow meters, regularcalibration cycles for any flow meter) over the life of the building andproduces a flow inference system that has a large range (turn down) andflow rate accuracy over the range that is associated with industrialflow meters that would be cost prohibitive for HVAC systems. Note: BTUmeters in buildings use low cost turbine or impeller wheel meters thatfowl so BTU meter in buildings are not that popular.

Constant flow through the cooling or heating load without cyclic rateallows for more accurate BTU rate monitoring than if a cyclic flow rateis applied because temperature sensors will experience delay in reading.This thermal delay is typically caused by a change in flow whichtypically causes a change in temperature through the coil.

FIGS. 1-5 show an embodiment of the assembly 10 in accordance with atleast one embodiment of the invention. The illustrated assembly 10 hasthe flow control valve 19 integrally connected to the BTU meter 14. Theflow control valve 19 is a high-performance pressure-independentconstant flow configured to maintain a constant flow rate across thevalve independent of any fluid pressure differentials or fluctuationsbetween the inlet 16 and the outlet 18 of the valve. In one embodiment,the pressure independent flow control valve 19 is a DeltaP Valve®,manufactured and sold by Flow Control Industries, Inc., of Woodinville,Wash. Other embodiments can use other pressure independent flow controlvalves that provide sufficient accuracy and performance.

The valve 19 includes a housing 20 that defines the inlet 16 and theoutlet 18 and that contains the internal components 22 of the valve,such as an internal passageway 24 connected to the inlet 16 and outlet18, a spring biased piston 26 movably disposed adjacent to a piston seat28 through which the water or other fluid can flow as the water movesthrough the flow passageway 24. The valve 19 includes a flow throttle 30rotatably disposed in a cavity within the flow passageway 24. The flowthrottle 30 has an opening 32 configured to selectively permit fluid toflow from the inlet 16, past the piston 26 and piston seat 28 (when thevalve is not closed), to the outlet. The flow throttle 30 is connectedto a valve stem 34 that is rotatably adjustable so as to rotate the flowthrottle 30 within the flow passageway 24. Accordingly, the flow ratethrough the valve 19 can be very accurately adjusted by rotating thevalve stem 34, thereby rotating and adjusting the flow throttle 30.

The valve 19 of the illustrated embodiment is a high performance valvewith high “turn down”, which equals the valve's highest flow ratedivided by the lowest flow rate achievable. For a fixed valve orifice,the turn down is calculated by taking the square root of the highestpressure drop across the orifice divided by the lowest pressure drop.For example, a valve that offers a pressure drop across the orifice of200 psi at maximum flow and 2 psi at minimum flow will have a turn downof 10:1. The valve 19 of the illustrated embodiment has a turn down ofapproximately 100:1, and the valve will operate in the pressureindependent range from approximately 5-70 PSID (0.34-4.83 bar),inclusive. In other embodiments, the valve 19 can have a higheroperating range of approximately 10-90 PSID (0.7-6.2 bar), inclusive.Other embodiments can include other high performance valves that havedifferent turn downs and/or different operating ranges.

The valve 19 of the illustrated embodiment that provides a constant flowrate through the valve independent of pressure drops across the valveand that has the turn down of approximately 100:1, allows the user tovery accurately control the fluid flow through the entire pressureindependent range, by adjusting the stem 34 and the flow throttle 32.

As seen in FIGS. 1-5, a support plate 40 has an attachment portion 42securely attached to the valve 19, and a platform portion 44 attached tothe arm portion 32. The BTU meter 14 mounted on the platform portion 44,so that the BTU meter is securely supported in a fix position adjacentto the valve 19. As seen in FIGS. 2 and 5, the platform portion 44 hasan aperture 46 therein coaxially aligned with the stem 34 of the valve19. The stem 34 extends away from the valve's housing, and a distal endportion 40 of the stem 34 extends through the platform portion'saperture 46 and into a rotatable fitting 48 in the BTU meter. The stem34 is fixedly attached to the rotatable fitting 48 so that when the stemis rotated (manually or automatically in response to instructions from acontroller), the stem 34, the throttle 32, and the fitting 48 all rotatetogether as a unit relative to the BTU meter 14.

The BTU meter 14 has a position sensor 50 connected to the fitting 48and calibrated to accurately and precisely detect the angular positionof the fitting 48 and the stem 34 of the valve. The position sensor 50is coupled to a controller 52 that received data about the rotationalposition of the fitting 48 and/or the stem 34. As indicated above, thevalve 19 is a high performance pressure independent valve with a highturn down, which provides for very accurate control of the water flowrate through the valve. Once the stem 34 and throttle 30 have beenrotated to a selected position the flow rate through the valve remainsconstant independent of pressure fluctuations. This highly accuratecontrol of the fluid flow rate is such that the valve 19 can becalibrated to very accurately identify or determine the fluid flow ratethrough the valve based on the position of the stem 34 (e.g., theangular position of the stem), and thus the throttle 30. The positionsensor 50 is also calibrated to accurately detect the position of thestem relative to a predetermined referenced point. Accordingly, thecontroller 52 uses the data from the position sensor about the positionof the stem 34 to very accurately determine the actual flow rate ofwater through the valve 19.

In the illustrated embodiment, the controller 52 of the BTU meter 14 iscoupled to temperature sensors 15 positioned at selected locations in aheating and cooling system 11, shown schematically. The controller 52receives data from the temperature sensors 15, such as one temperaturesensor for supply water and another for the return water of a heatexchanger. The controller 52 is configured to calculate the energyconsumption based on the flow rate data and the temperature sensor data.The result is a very accurate measurement of energy consumption in realtime by the BTU meter 14 because the calculation utilizes the actualflow rate information from the pressure independent constant flow rateto which the rotational position of the stem is accurately correlatedand calibrated.

In at least one embodiment, the assembly includes an air temperaturesensor 58 and air flow sensor 60 shown in FIG. 1. The air temperaturesensor 58 and air flow sensor 60 can also be monitored by the computer13 discussed above. In conjunction with fan on/off indication thissensor can be used to monitor cooling or heating coil performance. Theair temperature sensors can also be used to control the stem positionand to vary the flow fluid through the cooling or heating coil tomaintain a desired air temperature.

From the foregoing, it will be appreciated that specific embodiments ofthe invention have been described herein for purposes of illustration,but that various modifications may be made without deviating from theinvention. Additionally, aspects of the invention described in thecontext of particular embodiments or examples may be combined oreliminated in other embodiments. Although advantages associated withcertain embodiments of the invention have been described in the contextof those embodiments, other embodiments may also exhibit suchadvantages. Additionally, not all embodiments need necessarily exhibitsuch advantages to fall within the scope of the invention. Accordingly,the invention is not limited except as by the appended claims.

We claim:
 1. An energy consumption monitoring system for a fluid-basedheating or cooling system with a fluid flow therethrough, comprising: aheating or cooling device; a supply line connected to the heating orcooling device, the supply line carrying fluid to the heating or coolingdevice at a first temperature; a return line connected to the heating orcooling device, the return line carrying fluid from the heating orcooling device at a second temperature different than the firsttemperature; a first temperature sensor coupled to the supply line andpositioned to measure the first temperature; a second temperature sensorcoupled to the return line and positioned to measure the secondtemperature, wherein a temperature difference between the first andsecond temperatures is a temperature change across the heating orcooling device; a pressure independent, constant-flow control valveassembly comprising a valve body with an inlet and an outlet, a valvechamber therein, a fluid path extending between the inlet, outlet andthe valve chamber; an adjustable valve member in the valve chamber anddisposed in the fluid path, a valve stem connected to the valve member,the valve stem being rotatable relative to the valve body to adjust thevalve member and to adjust a fluid flow rate through the fluid path, theposition of the valve member relative to the fluid path being directlyrelated to the fluid flow rate through the fluid path, the valve stemhaving a free end portion projecting from the valve body; a first fluidpressure sensor positioned to measure the fluid pressure of fluidentering the inlet of the valve body; a second fluid pressure sensorpositioned to measure the fluid pressure of fluid exiting the outlet ofthe valve body, wherein a difference between the first and secondpressures is the pressure drop across the valve; and a BTU meterassembly connected to the free end portion of the valve stem, whereinthe valve stem is rotatable relative to at least a portion of the BTUmeter assembly, the BTU meter assembly comprising a BTU body, a positionsensor coupled to the BTU body and to the valve stem, the positionsensor being configured to detect the rotational position of the valvestem relative to the BTU body, the BTU meter assembly having acontroller coupled to the position sensor, to the first and secondpressure sensors, and to the first and second temperature sensors, thecontroller being configured to determine the fluid flow rate based uponthe pressure drop across the valve and the rotational position of thevalve stem, and the controller being configured to determine energyusage of the heating or cooling device in real time based upon the flowrate and the temperature change across the heating/cooling device. 2.The system of claim 1 wherein the BTU meter comprises a BTU body and arotatable fitting connected to the BTU body, the rotatable fitting beingfixedly attached to the free end portion of the valve stem and beingrotatable with the valve stem as a unit relative to the BTU and valvebodies.
 3. The system of claim 1 wherein position sensor is calibratedto detect the rotational position of the valve stem relative to apredetermined reference point directly related to a reference positionof the adjustable valve member in the valve chamber.
 4. The system ofclaim 1 wherein the BTU meter assembly is carried by the pressureindependent, constant-flow control valve assembly.
 5. The system ofclaim 1 wherein the heating or cooling device is a component of aheating and chilled water system.
 6. The system of claim 1 wherein theheating or cooling device is a heat exchanger, a boiler, a condenser, ora chiller.
 7. The system of claim 1 wherein at least the BTU body issecurely supported in a fixed position adjacent to the pressureindependent, constant-flow control valve assembly.
 8. The system ofclaim 1 wherein the valve stem is automatically adjustable in responseto instructions from the controller.
 9. The system of claim 1 whereinthe valve stem, the valve member, and the rotatable fitting areinterconnected and are rotatable together as a unit relative to the BTUbody.
 10. The system of claim 1 wherein controller is exterior of theBTU body.
 11. A constant-flow control valve and BTU meter assemblycoupleable to a fluid-based heating or cooling system with a heating orcooling device, fluid supply and return lines connected to the heatingor cooling device, and temperature sensors connected to the fluid supplyand return lines and configured to measure fluid temperatures of supplyfluid and return fluid relative to the heating or cooling device,wherein a temperature difference between the first and secondtemperatures is a temperature change across the heating or coolingdevice, the constant-flow control valve and BTU meter assemblycomprising: a pressure independent, constant-flow control valve assemblyconnectable to the fluid-based heating or cooling system, the pressureindependent, constant-flow control valve assembly having a valve bodywith an inlet and an outlet, a valve chamber with a fluid path thereinextending between the inlet and outlet, an adjustable valve member inthe valve chamber and disposed in at least a portion of the fluid pathto define a throttle in the fluid path, a valve stem connected to thevalve member and being rotatable as a unit relative to the valve body tochange the position of valve member to change a fluid flow rate throughthe valve body, wherein the position of the valve member relative to thefluid path is directly related to the fluid flow rate through the fluidpath, the valve stem having a free end portion projecting from the valvebody; a first fluid pressure sensor positioned to measure the fluidpressure of fluid entering the inlet of the valve body; a second fluidpressure sensor positioned to measure the fluid pressure of fluidexiting the outlet of the valve body, wherein a difference between thefirst and second pressures is the pressure drop across the valveassembly; and a BTU meter assembly connected to the free end portion ofthe valve stem, wherein the valve stem is rotatable relative to at leasta portion of the BTU meter assembly, the BTU meter assembly having a BTUbody, and a position sensor coupled to the BTU body and to the valvestem, the position sensor being configured to detect a rotationalposition of the valve stem relative to the BTU body, the BTU meterassembly having a controller coupleable to the position sensor, to thefirst and second pressure sensors, and to the first and secondtemperature sensors, the controller being configured to determine thefluid flow rate based upon the pressure drop across the valve assemblyand the rotational position of the valve stem, and the controller beingconfigured to determine energy usage of the heating or cooling devicebased upon the flow rate and the temperature change across the heatingor cooling device.
 12. The assembly of claim 11 wherein the BTU metercomprises a BTU body and a rotatable fitting connected to the BTU body,the rotatable fitting being fixedly attached to the free end portion ofthe valve stem and being rotatable with the valve stem as a unitrelative to the BTU and valve bodies.
 13. The assembly of claim 11wherein position sensor is calibrated to detect the rotational positionof the valve stem relative to a predetermined reference point directlyrelated to a reference position of the adjustable valve member in thevalve chamber.
 14. The assembly of claim 11 wherein the BTU meterassembly is carried by the pressure independent, constant-flow controlvalve assembly.
 15. The assembly of claim 11 wherein the heating orcooling device is a component of a heating and chilled water system. 16.The assembly of claim 11 wherein the heating or cooling device is a heatexchanger, a boiler, a condenser, or a chiller.
 17. The assembly ofclaim 11 wherein at least the BTU body is securely supported in a fixedposition adjacent to the pressure independent, constant-flow controlvalve assembly.
 18. The assembly of claim 11 wherein the valve stem isautomatically adjustable in response to instructions from thecontroller.
 19. The assembly of claim 11 wherein the valve stem, thevalve member, and the rotatable fitting are interconnected and arerotatable together as a unit relative to the BTU body.
 20. The assemblyof claim 11 wherein controller is exterior of the BTU body.
 21. A methodof determining energy consumption of a fluid-based heating or coolingsystem with a heating or cooling device and fluid flowing therethrough,method comprises: determining a first temperature of fluid flowing in asupply line to the heating or cooling device; determining a secondtemperature of fluid flowing in a return line from the heating orcooling device; determining a first fluid pressure of fluid entering aninlet of a pressure independent, constant-flow control valve assemblythat controls a flow rate of the fluid in the fluid-based heating orcooling system, the control valve assembly comprising a valve bodyconnected to the inlet and an outlet, a valve chamber in the valve body,and an adjustable valve member in the valve chamber and disposed influid path extending through the valve body between the inlet andoutlet, the control valve assembly having a valve stem connected to thevalve member, the valve stem being rotatable relative to the valve bodyto adjust the valve member and to adjust a fluid flow rate through thefluid path, the position of the valve member relative to the fluid pathbeing directly related to the fluid flow rate through the fluid path,the valve stem being connected to a BTU meter and being rotatablerelative to the BTU body and the valve body; determining a position ofthe valve stem relative to the valve body or the BTU body; determining asecond fluid pressure of fluid exiting the outlet of the control valveassembly, wherein a difference between the first and second fluidpressures corresponds to a pressure drop across the valve; determiningthe flow rate of fluid passing through the control valve assembly basedon the pressure drop across the valve and the position of the valve stemrelative to the valve body or the BTU body; and determining energyconsumption of the heating or cooling device in real time based upon thedetermined flow rate and the temperature change across the heating orcooling device.
 22. The method of claim 21 wherein the BTU meterassembly has a controller, and determining the first temperatureincludes sensing the first temperature with a first temperature sensorcoupled to the controller and coupled to the supply line, anddetermining the second temperature includes sensing the secondtemperature with a second temperature sensor coupled to the controllerand coupled to the return line.
 23. The method of claim 21 whereindetermining the flow rate includes detecting a rotational position ofthe valve stem relative to a predetermined reference point associatedwith at least one of the valve body or the BTU body.
 24. The method ofclaim 21 wherein determining energy consumption of the heating orcooling device includes determining the energy consumption of at leastone of a heat exchanger, a boiler, a condenser, or a chiller.
 25. Themethod of claim 21 wherein determining the position of the valve stemcomprises determining with a position sensor a rotational position ofthe valve stem relative to the valve body or BTU body.
 26. A method ofdetermining energy consumption of a fluid-based heating or coolingsystem with a heating or cooling device and fluid flow therethrough,method comprises: determining with a first temperature sensor a firsttemperature of fluid in a fluid supply line connected to the heating orcooling device, the supply line carrying the fluid to the heating orcooling device at the first temperature; determining with a secondtemperature sensor a second temperature of fluid in a fluid return lineconnected to the heating or cooling device, the supply line carrying thefluid away from the heating or cooling device at the second temperature;determining with a first fluid pressure sensor a first fluid pressure offluid entering an inlet of a pressure independent, constant-flow controlvalve assembly that controls a flow rate of the fluid in the fluid-basedheating or cooling system, the control valve assembly comprising a valvebody connected to the inlet and an outlet, a valve chamber in the valvebody, and an adjustable valve member in the valve chamber and disposedin fluid path extending through the valve body between the inlet and anoutlet, control valve assembly having a valve stem connected to thevalve member, the valve stem being rotatable relative to the valve bodyto adjust the valve member and to adjust a fluid flow rate through thefluid path, the position of the valve member relative to the fluid pathbeing directly related to the fluid flow rate through the fluid path,the valve stem being movably connected to a BTU meter; determining witha position sensor a rotational position of the valve stem relative tothe valve body or BTU body; determining with a second fluid pressuresensor a second fluid pressure of fluid exiting the outlet of thecontrol valve assembly, wherein a difference between the first andsecond fluid pressures corresponds to a pressure drop across the valve;determining the flow rate of fluid passing through the control valveassembly based on the pressure drop across the valve and the rotationalposition of the valve stem relative to the valve body or BTU body; anddetermining energy consumption of the heating/cooling device in realtime based upon the determined flow rate and the temperature changeacross the heating/cooling device.